Wireless devices use antennas to receive RF signals. The size of an antenna may depend on the wavelength of the RF signals that the wireless device is designed to receive. Typically, larger antennas are needed for signals with larger wavelengths. Accordingly, a mobile terminal may use antennas of a few inches for signals in the GHz range. However, for FM radio signals in the 100 MHz range, the antennas may need to be longer. As corded headsets gained popularity with mobile terminal users, many mobile terminal manufacturers used the headphone cord as an antenna, for example, for an FM receiver.
However, with the advent of Bluetooth headsets, the need for corded headsets has declined. The mobile terminal manufacturers have devised alternate means for implementing an FM antenna. One such antenna comprises a conductive coil or loop on a small circuit board that is typically placed at the back of the mobile terminal. Since this small FM antenna is limited in size, the antenna may be tuned to support the FM radio bandwidth. Additionally, because of the circuit board antenna's limited ability to receive FM signals, external factors may be a big factor to reception sensitivity. For example, a mobile terminal user holding the mobile terminal may cause the designed center frequency of the FM antenna to shift due to capacitive and/or inductive changes. Additionally, the mobile terminal's components, such as, the battery, may interfere with reception and/or change the antenna characteristics of the circuit board antenna by distorting and/or shorting the circuit board antenna.
Wireless systems are typically designed to function at a specific frequency, 900 MHz or 1.8 GHz, for example, and utilizing a defined standard such as GSM, WCDMA, EDGE, for example. Thus, wireless systems including antennas may have to be designed for a specific application with device performance optimized for that application.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with the present invention as set forth in the remainder of the present application with reference to the drawings.